So far, lack of huge uplift in household debt in the U.S. has been one positive in the current business cycle. Until, that is, one looks at the underlying figures in relevant comparative. Here is the chart from FactSet on the topic:

What does this tell us? A lot:

Nominal levels of household debt are up above the pre-crisis peak.

Leverage levels (debt to household income ratio) is at 17 years low.

Mortgage debt is increasing, and is approaching its pre-crisis peak: mortgage debt stood at $10.1 trillion in 1Q 2018, just 5.7% below the 2008 peak.

Consumer credit has been growing steadily throughout the 'recovery' period, averaging annual growth of 5.2% since 2010, bringing total consumer debt to an all-time high of nearly $14 trillion in early 2018.

While leverage has stabilized at around 95%, down from the 124% at the pre-crisis peak, current leverage ratio is still well-above the 58% average for 1946-1999 period.

The above conditions are set against the environment of rising cost of debt carry (end of QE and rising interest rates). In simple math terms, 1% hike in interest rates will require (using 95% leverage ratio and 25-30% upper marginal tax brackets) an uplift of 1.19-1.24% in pre-tax income for an average family to sustain existent debt carry costs.

The notion that the U.S. households are financially non-vulnerable to the cyclical changes in debt costs, employment and asset markets conditions is a stretch, even though the current levels of risks in leverage ratios are not exactly screaming a massive blow-out. Just as the U.S. Government has low levels of slack in the system to deal with any forthcoming shocks, the U.S. households have little cushion on assets side and on income / savings balances to absorb any significant changes in the economy.

As we say in risk management, the system is tightly coupled and highly complex. Which is a prescription for a disaster.